Jenkins Michael B, Liotta Janice L, Bowman Dwight D
USDA-Agriculture Research Service, J. Phil Campbell, Sr., Natural Resource Conservation Center, Watkinsville, Georgia 30677, USA.
J Parasitol. 2013 Apr;99(2):337-42. doi: 10.1645/GE-3193.1. Epub 2012 Sep 27.
Because of outbreaks of cryptosporidiosis in humans, some Cryptosporidium spp. have become a public health concern. Commercial swine operations can be a source of this protozoan parasite. Although the species distribution of Cryptosporidium is likely dominated by Cryptosporidium suis , a fraction may be comprised of other Cryptosporidium species infectious to humans such as Cryptosporidium parvum . To better understand the survival dynamics of Cryptosporidium spp., oocysts associated with swine operations, 2 experiments were performed to determine die-off rates of C. parvum oocysts in a swine waste lagoon (2009 and 2010) and its spray field (2010 and 2011). Sentinel chambers containing a lagoon effluent suspension of C. parvum oocysts were submerged in the lagoon, and triplicate chambers were removed over time; oocysts were extracted and assayed for viability. For comparative purposes, inactivation rates of Ascaris suum eggs contained in sentinel chambers were also determined. For 2 spray field experiments, air-dried and sieved surface soil was placed in sentinel chambers, hydrated, and inoculated with a lagoon effluent suspension of C. parvum oocysts. Sentinel chambers and control oocysts in PBS contained in microcentrifuge tubes were buried 1.5 cm below the soil surface in 3 blocks. Triplicate chambers and controls were removed over time; oocysts were extracted and assayed for viability. Based on the first order decay equation, days to reach 99% die-off (T(99)) were determined. T(99)-values determined for the 2 lagoon experiments were 13.1 and 20.1 wk, respectively. A T(99)-value for C. parvum in the spray field was significantly longer at 38.0 wk than the control oocysts in PBS at 29.0 wk. The waste lagoon and spray field system of manure management at this large-scale farrowing operation appeared to reduce the load of C. parvum oocysts before they can be hydrologically transported off the operation and reduces their likelihood of contaminating surface waters and threatening public health.
由于人体隐孢子虫病的爆发，一些隐孢子虫物种已成为公共卫生问题。商业化养猪场可能是这种原生动物寄生虫的一个来源。尽管猪隐孢子虫可能在隐孢子虫的物种分布中占主导地位，但其中一部分可能由其他可感染人类的隐孢子虫物种组成，如微小隐孢子虫。为了更好地了解隐孢子虫物种的存活动态，对与养猪场相关的卵囊进行了2项实验，以确定微小隐孢子虫卵囊在猪粪泻湖（2009年和2010年）及其喷洒场（2010年和2011年）中的死亡速率。将装有微小隐孢子虫卵囊泻湖流出物悬浮液的哨兵室浸没在泻湖中，并随着时间的推移取出一式三份的室；提取卵囊并检测其活力。为了进行比较，还测定了哨兵室中猪蛔虫卵的失活率。对于2项喷洒场实验，将风干并过筛的表层土壤放入哨兵室中，加水使其湿润，并接种微小隐孢子虫卵囊的泻湖流出物悬浮液。将装有微离心管中PBS的哨兵室和对照卵囊埋在3个地块土壤表面以下1.5厘米处。随着时间的推移取出一式三份的室和对照；提取卵囊并检测其活力。根据一级衰变方程，确定达到99%死亡所需的天数（T(99)）。在2项泻湖实验中确定的T(99)值分别为13.1周和20.1周。微小隐孢子虫在喷洒场的T(99)值为38.0周，明显长于PBS中对照卵囊的29.0周。在这个大型产仔场的粪肥管理的泻湖和喷洒场系统似乎在微小隐孢子虫卵囊通过水文方式从该养殖场运出之前降低了其负荷，并降低了它们污染地表水和威胁公众健康的可能性。
